Ore Mineralogy and Fluid Inclusion Characteristics of Different Ore Associations from Malanjkband Copper Deposit, M. P. (India)

Textural and paragenetic study of primary minerals (chalcopyrite, pyrite, magnetite, hematite, sphalerite, bornite, chalcocite and molybdenite) reveal intermittent fracturing, precipitation and dissolution phenomena with at least two recognizable stages: magnetite(I) - pyritc(I) - molybdenite (?) followed by pyrite(II) - chalcopyrite - sphalerite - magnetite(II) - hematite - bornite - chalcocite. Oxidation and supergene enrichment effects producing cuprite-malachite-native copper and chalcocite-covellite are moderate. Difference in the mineralogy of the oxidation zone and restricted occurrence of supergene enrichment are due to the variation in the primaty mineralogy of the ore.

The ranges of fluid inclusion homogenization temperature (maxima 160°-180°C) and fluid densities in the reef quartz and ore bearing vein quartz are more or less the same, with a wider range of salinity in the vein quartz ores. However, mixed aqueous carbonic inclusions are restricted to the vein quartz ores and hence points towards a difference in the fluid regime. T_h vs. salinity and T_h vs. density plottings rule out simple cooling and/or mixing processes in the evolution of the fluid but rather hint at immiscible two-fluid phase separation. The suspected presence of low temperature Iss-phases and the results of fluid inclusion microthermometty point towards an unexpectedly low temperature environment of ore deposition. The paragenetic sequence is suggestive of an increase in the Cuffe ratio and fluctuating f_O2 conditions in the fluid during the main stage of mineralization.